I'm also looking for advice on how to protect my data from a potential harddrive failure.
Unless, of course, you want to use compression.
You can try to back this up with 2 methods, i.e. burn DVDs of music and old photos every blue moon, and do a nightly crontab backup of the stuff that's likely to change.
Or you can use something like rsnapshot, which takes 1 snapshot of everything, and then saves deltas of what has changed. Dunno if that makes sense, here's how it works on my system -
1 initial snapshot, took a long time and a lot of GB, backup up all my music, files, email, whatever.
nightly snapshots - short and quick, a few MB a night, only backs up what has changed since the last nightly backup.
A full restore would involve restoring the initial backup + all the incrementals, but there's a script to do that.
Of course I'm doing all this from a cron job on my home file server, but I think there are similar tools for Windows, or there's always Cygwin.
That server has 2 HDs, a live one and a rsnapshot one, so if the house burns down I'm screwed, but if either HD fails I'm OK.
While this is a joke, it's something I did with my first 250G drive in a similar situation. I narrowed it down to Ubuntu within a week or so, and repartitioned the drive.